FastAPI

FastAPI has established itself since 2020 as the reference Python framework for building modern REST APIs. Its promise: performance comparable to Node.js, automatic input validation via Pydantic, OpenAPI documentation generated for free, and idiomatic Python syntax. For teams with a Python affinity (data, scientific, ML), it has become the obvious choice for exposing endpoints, where previously Flask or Django were the only credible options.

• →Django REST FrameworkIf you already have Django or want a monolith with native admin
• →FlaskMore minimalist, but less productive on modern cases, useful for scripts or very small APIs
• →API PlatformPHP equivalent, better choice if the team is already on SymfonyView page
• →Express + TypeScriptNode.js equivalent, valid choice if the team is JS rather than Python

1. 01

   Pydantic systematically to model requests/responses: it's the framework's strength

2. 02

   Async where useful (IO, DB, external HTTP), not by default on all routes

3. 03

   SQLModel or SQLAlchemy 2.x for ORM: avoid abandoned libraries

4. 04

   Tests with pytest + httpx: the FastAPI test ecosystem is mature

5. 05

   Deployment with uvicorn behind nginx or Caddy, or Docker depending on preferences

• FastAPI vs Django REST Framework?

  FastAPI for new pure API backends: more modern, faster, type-safe by default, auto doc. Django REST Framework remains the right choice for existing Django apps or for monoliths with integrated Django admin. For a purely API project since 2022, FastAPI is almost always more relevant.
• How much does a FastAPI project cost?

  For a medium business API (10-20 endpoints, auth, OpenAPI doc), expect €3,000 to €10,000. For a larger API with ML or data science integrations, €8,000 to €20,000. Pydantic efficiency and auto doc generation reduce delays on first milestones compared to manual assembly.
• Does FastAPI scale in production?

  Yes. Companies like Uber, Microsoft and Netflix use FastAPI in production. Performance is comparable to Node.js on I/O workloads (most web APIs). For extreme cases (millions of requests per second on pure compute), Go or Rust remain faster, but that's rarely an SMB concern.
• Async or sync in FastAPI?

  Async for IO operations (async database, external HTTP calls), sync for the rest. FastAPI handles both without difficulty thanks to a thread pool. Classic trap: using a sync library in an async route without knowing it, which blocks the server. To audit in code review.
• And security?

  FastAPI offers native dependencies for OAuth2, JWT, and token auth. For simple needs, that's enough. For more complex cases (multi-tenant, fine RBAC), libraries like fastapi-users or Authlib are mature. Pydantic validation already protects from most classic injections by filtering inputs.